1. Field of the Invention
The present invention relates to a shielding cover provided with cooling fins to cool down heat generated from a drive unit such as a motor in various apparatuses.
2. Description of the Related Art
In various apparatus which are incorporating a drive unit such as a motor, etc. for driving operating devices, when a driving unit is operated, for example, a motor bearing is heated causing temperature rise and also noise is generated from the rotating motor. In particular, in the case of a drive motor which drives an operating unit that is rotated and driven at a high speed such as a polygon mirror to reflect and polarize optical beam emitted from a laser beam emitting element in the direction of a photo conductor for forming electrostatic latent images, the heat is generated from a bearing when a motor is driven and furthermore, the generating noise becomes large. Such the temperature rise resulting from the rotation of a drive motor gives an adverse effect to electronic parts around the motor and may damage them.
In the Japanese Patent Application Publication No. 11-160644, an optical beam scanner with special shaped cooling fins provided on a polygon mirror housing is disclosed. This conventional optical beam scanner is provided with sealing members on the peripheral wall of the housing with cooling fins in a special shape projecting from the bottom surface of the housing around the bearing unit of the polygon mirror member. Thus, the conventional optical beam scanner promotes the cooling effect by the cooling fins and prevents leakage of noises by the sealing member.
However, this conventional optical beam scanner promotes the cooling effect by increasing the cooling area of the cooling fins but the cooling fins are formed in the special shape and the flow of air passing through the cooling fins is not taken into consideration. Further, although the leakage of noise is prevented totally, the noise insulation against those portions especially generating intense noises is not considered.
So, a shielding cover and an optical scanner provided with cooling fins, which increase reliability by preventing damage of surrounding parts and also are excellent in soundproofing are so far demanded.